This longitudinal study of adult development involves prospective studies of 268 Harvard College sophomores and 456 inner-city Boston school boys each of which have lasted for half a century with minimal attrition. Data for each subject consists of 4 generation social histories, biennial questionnaires, face to face interviews every fifteen years, and complete physical examinations every five years. Research has focused upon (1) adaptation to stress, mental health, and defense mechanisms; (20 the effects of habits (especially alcoholism) and affective disorders upon physical health and mortality; (3) the effect of childhood risk factors upon adult adaptation; (4) the unfolding of adult development; and (5) the natural history of alcohol and substance abuse. Other ongoing projects that have evolved from these longitudinal archives include long-term outcome studies of World War II PTSD, effects of attributional style on physical health, and successful adult careers by the mildly retarded.